Urban areas often have poor Global Positioning System (GPS) reception in their core areas, where tall buildings are situated along both sides of nearly every street or roadway. For example, while GPS works well for the highways approaching New York City, as a vehicle actually gets into New York City, numerous obstructions prevent the receipt of satellite signals. Such areas are often known as “urban canyons.” Similar effects are known in other major metropolitan centers.
Currently, vehicles rely on the availability of accurate GPS signals for position determination. Where such signals cannot be received, alternate solutions must be utilized.
One possible solution that has been proposed is a 2.4 gigahertz solution, using 10 MHz of bandwidth to transmit pulses that could be used to calculate position in such urban areas. However, such a small bandwidth would define the accuracy, and the accuracy with 10 MHz of bandwidth is generally poor, on the order of 6-10 meters. This level of accuracy makes it inadequate to predict accidents or to even know what lane one is in. V2V can support multiple safety apps to warn of pending accidents, including Forward Collision Warning, Emergency Electronic Brake Light, Intersection Movement Assist, Do Not Pass Warning and Left Turn Assist, and having accurate position data is critical for these technologies to work.
What is needed in the art are alternate ways of providing position information to vehicles that can facilitate accuracy to 1 meter or less, and preferably to accuracies within centimeters, especially in areas where GPS signals are weak or unavailable.